This invention relates to a device used to sample and monitor subsurface ground water. More particularly it relates to a device for taking samples from ground water adjacent to a drilled well and communicating those samples to the surface for analyzation. The procedures involved in subsurface ground water monitoring wells and the equipment require subsurface water samples to be used to perform the required precise tasks of chemical testing of those samples. The four primary procedures are bailing or purging water from the well, collecting ground water samples for testing, measuring the depth of the water, and performing hydraulic conductivity tests. An additional test would be a discrete sampling of the water at specific depth zones within the underground water table. These are all common tests required often in areas where there is a potential chance of the contamination of the natural aquifer.
This device as herein disclosed features a new and unique Pneumatic Bailer device and process that will replace the expensive equipment and time-consuming procedures in the tasks involved with ground water monitoring wells. Ground water passing through the screen cuts in the well casings is presently raised by using an expensive stainless steel submersible electric pump lowered into the well casing on a suspension cable along with a power cable and discharge/sampling hose. The so described procedures are accomplished and the pump is returned to the surface where it must be decontaminated before being used again. This decontamination process entails washing the inside and outside of all the equipment used with a solution of TSP (Tri-Sodium Phosphate) and then rinsing twice with deionized or distilled water to produce an accurate sampling thereafter. Often a generator is required to supply power for the submersible pump when used in remote locations. With this equipment, access to the inlet of the well casing is always required and the successful operation of equipment on wells that have been drilled on an angle to get beneath an existing obstacle is sometimes hampered.
U.S. Pat. No. 3,075,585 of L. A. Carlton ET AL describes an invention related to fluid samples, and more particularly to apparatus for taking samples of fluids at remote locations such as in a deep well in the earth. This invention relates to a device to be lowered down into wells to take a small sample in a controlled environment, and therein transport it to the surface. This invention has no means to pump water or any other fluid to the surface as in the so disclosed Bailer Unit.
U.S. Pat. No. 3,296,971 of A. L. Nielson discloses a mounting means for a sub floor pump. This device as disclosed teaches of a sub-floor, or basement pump to elevate water from the premises, not for lifting a fluid from a monitoring well which may be just below the surface or go as deep as 250 feet.
The outstanding convenience and economy of the device herein disclosed is made evident in the description of the well sampling and testing device or Pneumatic Bailer Unit used to perform the tasks required in well monitoring, without the time consuming decontamination process. The sophisticated, expensive equipment requires a great deal of time to decontaminate prior to being used for testing at another well monitoring site. These and other additional benefits will be elaborated upon further in this disclosure.
The preferred embodiment of the simplest version of this invention is where a hermetically sealed bailer unit is placed remotely below the surface in a bore-hole surrounded by a sand filter casing with a discharge or sampling pipe along with a pneumatic line going to the surface monitoring stations. The material that the Bailer Unit and the parts therein are constructed of, is most commonly PVC (Poly Vinyl Chloride) similar to that used on well casing stock, although in some cases the unit can be constructed of other rust resistant material like stainless steel and maintain the same disclosed configuration. A pipe translates through a sealed orifice in the wall surface at the top of the Bailer Unit, down through the unit to the lower distal end thereupon attached to a one-way valve opening in a close proximity to the bottom of the Bailer Unit and allowing the discharge of the water to the surface monitoring station. The pneumatic pressure/vacuum line enters the Bailer in the upper side wall of the unit. All penetrations and connections into the Bailer Unit maintain the hermetic sealing required by, but not limited to, the process of plastic welding or gluing. The surface monitoring station consists of a concrete vault with connectors to the discharge and pneumatic lines and a lockable cover plate. These sites may be placed in areas where the opening at the top of the conventional well casings would be inaccessible, as in directly below fuel storage tanks, and below buildings or roadbeds. Even with the remote placement of these units, they can be decontaminated if required, by injecting a soap solution of TSP through the pneumatic line into the Bailer chamber and rinsing with distilled or de ionized water. After this procedure, the liquid can be blown out with air through the same pneumatic line, ejecting through the discharge/sampling pipe to the surface monitoring station.
An alternate embodiment has the same Bailer Unit cooperatively attached at the lower most, or the distal end of the well casing by a coupler unit. A single tubular member translates from within the well casing through the coupler and into the Bailer retaining the hermetic ceiling of the unit. This tube is then attached to a one-way valve in close proximity to the top of the Bailer Unit, restricting any back flow from the Bailer into the well casing. The pressure/vacuum line penetrates the upper side wall of the Bailer chamber as in the initial embodiment. A second tubular member will penetrate the side wall of the Bailer in close proximity to the bottom of the Bailer Unit, with a second one-way valve. The second valve restrains any flow back into the Bailer from the discharge or sampling pipe going to the surface. An additional pneumatic pressure line attaches through the coupler unit into the well casing reservoir. This additional pneumatic line is used to make water pressure readings and to stir any sediment collected in this area. The two separate pneumatic lines for gas or compressed air are attached near the union of the well casing coupler, and the Bailer through the walls of the well casing and Bailer respectively, connecting to the surface monitoring station by means of a pipe or tubing, described as pneumatic lines. This assembly remains permanently affixed to the bottom of the well casing assuring that no external contamination other than what might be in the ground water will be in the Bailer Unit.
With the application of compressed air or gas pressure through the line into the Bailer Unit, the water therein is forced out and up the discharge/sampling pipe to the surface. With a vacuum replacing the compressed air or gas, and the water pressure in the well casing, the water is drawn rapidly down into the Bailer Unit. Then with the re application of the air or gas pressure the Bailer chamber can be purged of the water and sediment collected within to the surface monitoring station. This process may be repeated several times to assure a fresh sample.
An additional alternate embodiment of the invention will have the Bailer Unit attached to the bottom of the well casing, with a separate reservoir cooperatively attached below. The lower reservoir will have the same screen configuration of the well casing material allowing water to enter freely. A pipe communicating between the two cavities with the first one-way valve being in the lower reservoir chamber, allowing water to move up only into the Bailer chamber, and the second one-way valve located in the Bailer allowing the water to be forced out to the surface monitoring station through the discharge/sampling pipe. A pressure line will enter into the top of the Bailer Unit with the additional pressure line entering the bottom of the well casing. Though the normal pressure will push the water up into the Bailer, the capability of the added vacuum will accelerate the sampling and purging process. This configuration will allow the well to operate independent of the Bailer Unit, so that a sample may be taken when the well is in operation.
An additional enhancement of the Bailer Unit will have a zone reducing tube lowered down into the well casing surface opening to perform discrete sampling of the water at specific zones within the water table. The zone reducing tube is comprised of a series of sections of PVC tubing and couplers reaching the full length of the well casing. A perforated PVC sampling section of tubing can be inserted at any level of the zone reducing assembly. At the lower end of the zone reducing tube is a centralizer, and a soft plastic ball with a hole through the center, affixed to the end of the PVC tubing. The soft rubber tube is attached on the pipe communicating between the well casing and the Bailer Unit. As the zone reducing tube is lowered into the well casing, the centralizer locates the soft ball over the rubber tube to create an adequate seal for the sampling of the specific zone in the water table. The centralizer, consists of a PVC circular device, smaller in diameter than the inside of the well casing with orifices allowing the water to pass through. The centralizer is attached to the PVC tubing just above the ball, so that when the zone reducing tube is lowered it will locate the ball over the top of the tube on the sample inlet valve.
All of the embodiments of the Bailer Unit would be coupled with a Well Monitoring Control Panel Console. The console has an intake port to be coupled with a compressed air source means, such as an air compressor or air tank, or compressed gas tank of inert gas such as nitrogen. It is possible that even a small battery operated air compressor might be used to accomplish the tasks adequately. Compressed air from the atmosphere is generally used to purge water from the device and to create a vacuum, because of its lower cost. Use of compressed gas would be preferred in cases where ground water samples are being collected which require extreme accuracy as to contents, due to its inert chemical properties.
A 4-way valve allows the operator to switch from off, to pressure or vacuum, until the desired amount of ground water is removed. An optional on/off valve on the pressure/vacuum line offers a redundancy in the closing of the line for testing purposes. The pressure regulator on the pressure/vacuum line allows for the control of the pressure used to perform the required procedures. A sensitive pressure/vacuum gauge will give the operator the information needed to determine the depth to ground water by measuring the pressure needed to raise ground water in the discharge tube just to the surface, and converting this pressure reading into an equivalent height of water. A three-way valve is incorporated at the discharge end of the pressure/vacuum line to allow pressure to be switched from the Bailer Unit line, to the well casing coupler line, for determining the ground water pressure reading, and stirring the accumulated sediment in the bottom of the well casing. A secondary vacuum line on-off valve is incorporated before the venturi unit to assure of a redundancy in the sealing means on the vacuum line. The vacuum is used to accelerate the entry of the water into the Bailer chamber. Hydraulic conductivity of the aquifer adjacent to the well can be estimated by performing a xe2x80x9cslug testxe2x80x9d with the Bailer Unit system, and using one of several methods of calculation. The procedure consists of rapidly changing the height of water in the well by removing one or more Bailer volumes of ground water from the well, then periodically, recording the pressure indicated on the pressure gauge as the well returns to an equilibrium. The incremental pressure readings can then be converted into the height of water in the well, at a given time. The variation of height of water, over time, is used in the xe2x80x9cslug testxe2x80x9d calculations. The system is presently configured to measure ground water height equivalent to xc2xc inch (0.01 psi).
It is the object of this invention to create a device that in the simplest form can be located in wells inaccessible areas with a remote monitoring capability.
It is another object of this invention to create an inexpensive device that may stay at the site location, and not require the continuous time-consuming decontamination of a single pumping system.
It is still another object of this invention to create a device that can operate located beneath a monitoring well, sampling from within the well casing.
It is still another object of this invention to create a device that can be attached below a well casing, taking samples from a component reservoir without disturbing the operation of the well itself.
It is still another object of this invention to create a device that has the capability of taking samples from different zones within the water table being sampled by a well.
It is still another object of this invention to provide a control console to operate and record all the procedures and operations, required in well monitoring
These together with other objects and advantages, which will become subsequently apparent, reside in the details of construction and operation as more fully described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numbers refer to like parts throughout.